For example, Japanese Utility Model Application Laid-open No. Sho 53-49868 discloses a conventional elevator door safety device in which two light emitters are arranged on an upper frame of a landing three-way frame and in which two light receivers are arranged on vertical frames of the landing three-way frame. Detection lights emitted from the two light emitters cross each other at the center of a landing doorway and are received by the light receivers. When the detection lights are intercepted by an obstruction, such as a passenger, during door closing operation, the operating directions of the landing door and the car door are reversed, thereby preventing the obstruction from being caught between the doors.
While the above-described safety device is capable of preventing an obstruction from being caught between the doors during door closing operation, it is not capable of preventing the obstruction from being caught between a door and a doorway frame during door opening operation.
In this regard, JP 10-139333 A, for example, discloses a conventional device for protecting passengers from getting caught, in which a light emitter is arranged on one side of the car doorway or of the landing doorway and in which a light receiver is arranged on the other side thereof. Detection light is emitted horizontally from the light emitter along the door surface and is received by the light receiver. When the detection light is intercepted by an obstruction during door opening operation, the door operating direction is reversed, thereby preventing the obstruction from being caught between the door and the doorway frame.
The above-described device for protecting passengers from getting caught has a problem in that the door opening operation is reversed not only when the obstruction is near the vertical frame of the doorway frame but also when the obstruction is at the center of the doorway. That is, the door opening operation is reversed whenever the obstruction is situated in the vicinity of the door. Further, to secure the requisite accuracy in detection, it is necessary to arrange a large number of light emitters and light receivers in the vertical direction of the doorway.
JP 11-310375 A discloses a conventional door safety device in which a light emitter and a light receiver are arranged in a door case portion between the vertical frame of the doorway frame and the door. That is, the light emitter is arranged on an upper portion of the vertical frame, and the light receiver is arranged on a lower portion of the vertical frame. Detection light from the light emitter is emitted vertically downwards along the vertical frame and is received by the light receiver.
The problem with the above door safety device is that the detection light is intercepted only after the obstruction has been caught in the door case portion, which means it is impossible to prevent the obstruction from being caught.